A template for an employee form could also contain a portion asking for the employee's office extension number. This would probably be part of the form especially in big companies where an employee may be reached by another in a different branch office through phone.
The social security number will be part of the template. It will provide the company everything it has to know about the employee. If he has an outstanding warrant of arrest from the police, if he is an outstanding debt, what responsibility he has, what violations he did, etc.